Being “numbered among the laity” is talking about seating position (in church at Mass) and whether or not you could enter the altar area (during Mass).
The Montanist ladies whom Tertullian mentions, Prisca and Maximilla, were notorious for announcing that they were not just prophetesses (normal for the early Church) and priestesses (not normal), but also living incarnations of the Holy Spirit, just like their leader Montanus. (They also happily proclaimed themselves to be possessed when they prophesied and did a lot of crazy things, which was directly against the Jewish and Christian traditions of prophecy as being dignified.) Montanus, for his part, also announced that the village of Pepuza, Phrygia was the New Jerusalem, and that all Christians throughout the world should move there. All three of them announced that their New Prophecy was intended to say all the stuff that Jesus didn’t say, and had more authority.
So yeah, these ladies are not a good example. They were nuts.
Moving along, the other major early Christian splinter group with priestesses were the few groups of Mary-worshippers, among whom were the Arabic Collyridians (women who offered bread or cakes to the “goddess” Mary, instead of the old-fashioned raisin cakes to Astarte), and the Tyropitans who added milk and cheese to the list of sacramental foods given at Mass.
To be fair, milk or curds used to be given to newly baptized or newly married Christians, in many traditions, as a non-sacramental Biblical reference. Often it was milk and honey. But the Tyropitans just took it way too far.
The third group with priestesses were some of the Gnostic sects. Most of them were not enthusiastic about having women around at all, since of course matter is dirty and bad, and women are full of matter and blood and the potential to become pregnant. However, some Gnostics did like having women and their money around. The Gnostic Valentinus did recruit women into his group and had them serve as priestesses who passed around their Gnostic chalice, which was one of those “everflowing” magician props. Some Gnostic sects (the ones that figured that nothing you did in your nasty dirty body had any effect on the soul, and that experiencing lots of nastiness encouraged your pure clean soul to leave the material world faster) had the priestesses have sex with the male congregants. (Probably an adaptation of typical Middle Eastern temple prostitution.)
The only orthodox normal associations of women with the priesthood were the titles of “presbytera” (the wife of a married priest, as is still used today in the East), “presbyterissa” (the mom of a priest, who had special privileges), and “presbyteride” (a woman elder, like a deaconess, who rode herd over the women’s seating area). The presbyterides ended up being stamped out, because apparently some old church ladies were real jerks once they actually had an eensy bit of authority and not just officiousness.
